Many sheets of loop materials are known that are adapted to be cut into pieces to form the loop portions for fasteners of the type comprising releasably engageable hook and loop portions. Such sheets of loop materials typically comprise a backing and a multiplicity of loops formed from longitudinally oriented polymeric fibers bonded to or anchored in the backing and projecting from a front surface of the backing so that they may be releasably engaged with the hooks on the hook portion of such a fastener, and can be made by many methods including conventional weaving, or knitting techniques. Sheets of loop materials in which the loops are stitched into the backing are described in U.S. Pat. Nos. 4,609,581 and 4,770,917. While the loop fastener portions made from many such sheets of loop materials work well with many different hook fastener portions, many of the processes by which the sheets of loop material are made are more expensive than may be desired, particularly when the loop fastener portions are intended for a limited amount of use, such as to attach a disposable diaper, brief or garment to a person.
U.S. Pat. No. 5,256,231 (Gorman et al, the content whereof is incorporated herein by reference) discloses a sheet of loop material and a method and equipment for making it that provide effective loop fastener portions for such fasteners while being very inexpensive to manufacture either in a form intended for a limited amount of use, such as to releasably attach a disposable diaper or other disposable garment to a person, or in a form intended to be used a larger number of times. That sheet of loop material includes a backing comprising a thermoplastic backing layer with generally uniform morphology, and a sheet of longitudinally oriented fibers having generally non-deformed anchor portions bonded or fused in the thermoplastic backing layer at spaced bonding locations, and arcuate portions projecting from a front surface of the backing between the bonding locations; and is made by forming a sheet of longitudinally oriented polymeric fibers so that the sheet of fibers has arcuate portions projecting in the same direction from spaced anchor portions of the sheet of fibers, and then forming at least a portion of a backing around the spaced anchor portions of the sheet of fibers by extruding thermoplastic material onto the anchor portions of the sheet of fibers so that the arcuate portions of the sheet of fibers project from a front surface of the newly formed backing.
Such forming of the sheet of fibers is done by providing first and second generally cylindrical corrugating or forming members each including a plurality of uniformly spaced ridges defining its periphery, mounting the corrugating members in axially parallel relationship with portions of the ridges of the corrugating members in mesh with each other, rotating at least one of the corrugating members, feeding the sheet of fibers between the meshed portions of the ridges of the rotating corrugating members to generally conform the sheet of fibers to the periphery of the first corrugating member, thereby forming the arcuate portions of the sheet of fibers in spaces between the ridges of the first corrugating member and the anchor portions of the sheet of fibers along outer surfaces of the ridges of the first corrugating member, and retaining the formed sheet of fibers along the periphery of the first corrugating member after it has moved past the meshing portions of the ridges. At least a portion of the backing (or the entire backing) is then formed around the anchor portions of the sheet of fibers by extruding the molten thermoplastic material onto the anchor portions of the sheet of fibers while those anchor portions are on the end surfaces of the ridges on the first corrugating member.
U.S. Pat. No. 5,256,231 (Gorman et al) discloses that the ridges of the corrugating members can be elongate and generally parallel so that the bonding locations are also elongate and generally parallel and are continuous in one direction across the front surface of the backing so that continuous rows of the arcuate portions extend across the backing of the sheet of loop material; or alternately the ridges can be elongate, generally parallel, and in a regular pattern of discontinuous lengths so that the parallel bonding locations are also in a regular pattern of discontinuous lengths to form a regular pattern of discontinuous rows of the arcuate portions of the sheet of fibers along the front surface of the backing. Also, U.S. Pat. No. 5,256,231 (Gorman et al) contemplated that the ridges of the first corrugating member could form interlocking closed patterns (e.g., in the shape of circles, diamonds, octagons, letters, numbers, etc.) to form corresponding patterns for the arcuate portions of the fibers along the front surface of the backing, in which case the second corrugating member would be formed with post like ridges to press the sheet of fibers into the centers of the closed patterns.
As contemplated, this form of the corrugating or forming members can be used to form suitable loop materials when used as disclosed in U.S. Pat. No. 5,256,231. Some difficulties arise, however, when that equipment is run at higher speeds as is desired for production equipment, particularly when the sheet of fibers being fed into the equipment is a relatively low cost non woven sheet of cut fibers in which the fibers are not bonded together as is produced by a carding machine or off of a spunbond process in which the fibers are not consolidated. At those higher speeds difficulties have been found in maintaining the desired shape of a formed sheet of such fibers while it is retained along the periphery of the first forming member after it has moved past the meshing portions of the ridges and before the molten thermoplastic material is extruded onto its anchor portions. Also, unbonded webs can tend to loose fibers during the process.